How to compare two strings in dot separated version format in Bash?

Is there any way to compare such strings on bash, e.g.: 2.4.5 and 2.8 and 2.4.5.1?

Here is a pure Bash version that doesn't require any external utilities:

#!/bin/bash
vercomp () {
    if [[ $1 == $2 ]]
    then
        return 0
    fi
    local IFS=.
    local i ver1=($1) ver2=($2)
    # fill empty fields in ver1 with zeros
    for ((i=${#ver1[@]}; i<${#ver2[@]}; i++))
    do
        ver1[i]=0
    done
    for ((i=0; i<${#ver1[@]}; i++))
    do
        if [[ -z ${ver2[i]} ]]
        then
            # fill empty fields in ver2 with zeros
            ver2[i]=0
        fi
        if ((10#${ver1[i]} > 10#${ver2[i]}))
        then
            return 1
        fi
        if ((10#${ver1[i]} < 10#${ver2[i]}))
        then
            return 2
        fi
    done
    return 0
}

testvercomp () {
    vercomp $1 $2
    case $? in
        0) op='=';;
        1) op='>';;
        2) op='<';;
    esac
    if [[ $op != $3 ]]
    then
        echo "FAIL: Expected '$3', Actual '$op', Arg1 '$1', Arg2 '$2'"
    else
        echo "Pass: '$1 $op $2'"
    fi
}

# Run tests
# argument table format:
# testarg1   testarg2     expected_relationship
echo "The following tests should pass"
while read -r test
do
    testvercomp $test
done << EOF
1            1            =
2.1          2.2          <
3.0.4.10     3.0.4.2      >
4.08         4.08.01      <
3.2.1.9.8144 3.2          >
3.2          3.2.1.9.8144 <
1.2          2.1          <
2.1          1.2          >
5.6.7        5.6.7        =
1.01.1       1.1.1        =
1.1.1        1.01.1       =
1            1.0          =
1.0          1            =
1.0.2.0      1.0.2        =
1..0         1.0          =
1.0          1..0         =
EOF

echo "The following test should fail (test the tester)"
testvercomp 1 1 '>'

Run the tests:

$ . ./vercomp
The following tests should pass
Pass: '1 = 1'
Pass: '2.1 < 2.2'
Pass: '3.0.4.10 > 3.0.4.2'
Pass: '4.08 < 4.08.01'
Pass: '3.2.1.9.8144 > 3.2'
Pass: '3.2 < 3.2.1.9.8144'
Pass: '1.2 < 2.1'
Pass: '2.1 > 1.2'
Pass: '5.6.7 = 5.6.7'
Pass: '1.01.1 = 1.1.1'
Pass: '1.1.1 = 1.01.1'
Pass: '1 = 1.0'
Pass: '1.0 = 1'
Pass: '1.0.2.0 = 1.0.2'
Pass: '1..0 = 1.0'
Pass: '1.0 = 1..0'
The following test should fail (test the tester)
FAIL: Expected '>', Actual '=', Arg1 '1', Arg2 '1'

If you have coreutils-7 (in Ubuntu Karmic but not Jaunty) then your sort command should have a -V option (version sort) which you could use to do the comparison:

verlte() {
    [  "$1" = "`echo -e "$1\n$2" | sort -V | head -n1`" ]
}

verlt() {
    [ "$1" = "$2" ] && return 1 || verlte $1 $2
}

verlte 2.5.7 2.5.6 && echo "yes" || echo "no" # no
verlt 2.4.10 2.4.9 && echo "yes" || echo "no" # no
verlt 2.4.8 2.4.10 && echo "yes" || echo "no" # yes
verlte 2.5.6 2.5.6 && echo "yes" || echo "no" # yes
verlt 2.5.6 2.5.6 && echo "yes" || echo "no" # no

There probably is no universally correct way to achieve this. If you are trying to compare versions in the Debian package system try dpkg --compare-versions <first> <relation> <second>.

GNU sort has an option for it:

printf '2.4.5\n2.8\n2.4.5.1\n' | sort -V

gives:

2.4.5
2.4.5.1
2.8

Well if you know the number of fields you can use -k n,n and get a super-simple solution

echo '2.4.5
2.8
2.4.5.1
2.10.2' | sort -t '.' -k 1,1 -k 2,2 -k 3,3 -k 4,4 -g

2.4.5
2.4.5.1
2.8
2.10.2

function version { echo "$@" | awk -F. '{ printf("%d%03d%03d%03d\n", $1,$2,$3,$4); }'; }

Used as such:

if [ $(version $VAR) -ge $(version "6.2.0") ]; then
    echo "Version is up to date"
fi

(from https://apple.stackexchange.com/a/123408/11374)

This is for at most 4 fields in the version.

$ function ver { printf "%03d%03d%03d%03d" $(echo "$1" | tr '.' ' '); }
$ [ $(ver 10.9) -lt $(ver 10.10) ] && echo hello  
hello

You can recursively split on . and compare as shown in the following algorithm, taken from here. It returns 10 if the versions are the same, 11 if version 1 is greater than version 2 and 9 otherwise.

#!/bin/bash
do_version_check() {
        
   [ "$1" == "$2" ] && return 10

   ver1front=`echo $1 | cut -d "." -f -1`
   ver1back=`echo $1 | cut -d "." -f 2-`
   
   ver2front=`echo $2 | cut -d "." -f -1`
   ver2back=`echo $2 | cut -d "." -f 2-`

   if [ "$ver1front" != "$1" ] || [ "$ver2front" != "$2" ]; then
       [ "$ver1front" -gt "$ver2front" ] && return 11
       [ "$ver1front" -lt "$ver2front" ] && return 9

       [ "$ver1front" == "$1" ] || [ -z "$ver1back" ] && ver1back=0
       [ "$ver2front" == "$2" ] || [ -z "$ver2back" ] && ver2back=0
       do_version_check "$ver1back" "$ver2back"
       return $?
   else
           [ "$1" -gt "$2" ] && return 11 || return 9
   fi
}    

do_version_check "$1" "$2"

Source

• Function V - pure bash solution, no external utilities required.
• Supports = == != < <= > and >= (lexicographic).
• Optional tail letter comparison: 1.5a < 1.5b
• Unequal length comparison: 1.6 > 1.5b
• Reads left-to-right: if V 1.5 '<' 1.6; then ....

<>

# Sample output
# Note: ++ (true) and __ (false) mean that V works correctly.

++ 3.6 '>' 3.5b
__ 2.5.7 '<=' 2.5.6
++ 2.4.10 '<' 2.5.9
__ 3.0002 '>' 3.0003.3
++ 4.0-RC2 '>' 4.0-RC1

<>

function V() # $1-a $2-op $3-$b
# Compare a and b as version strings. Rules:
# R1: a and b : dot-separated sequence of items. Items are numeric. The last item can optionally end with letters, i.e., 2.5 or 2.5a.
# R2: Zeros are automatically inserted to compare the same number of items, i.e., 1.0 < 1.0.1 means 1.0.0 < 1.0.1 => yes.
# R3: op can be '=' '==' '!=' '<' '<=' '>' '>=' (lexicographic).
# R4: Unrestricted number of digits of any item, i.e., 3.0003 > 3.0000004.
# R5: Unrestricted number of items.
{
  local a=$1 op=$2 b=$3 al=${1##*.} bl=${3##*.}
  while [[ $al =~ ^[[:digit:]] ]]; do al=${al:1}; done
  while [[ $bl =~ ^[[:digit:]] ]]; do bl=${bl:1}; done
  local ai=${a%$al} bi=${b%$bl}

  local ap=${ai//[[:digit:]]} bp=${bi//[[:digit:]]}
  ap=${ap//./.0} bp=${bp//./.0}

  local w=1 fmt=$a.$b x IFS=.
  for x in $fmt; do [ ${#x} -gt $w ] && w=${#x}; done
  fmt=${*//[^.]}; fmt=${fmt//./%${w}s}
  printf -v a $fmt $ai$bp; printf -v a "%s-%${w}s" $a $al
  printf -v b $fmt $bi$ap; printf -v b "%s-%${w}s" $b $bl

  case $op in
    '<='|'>=' ) [ "$a" ${op:0:1} "$b" ] || [ "$a" = "$b" ] ;;
    * )         [ "$a" $op "$b" ] ;;
  esac
}

Code Explained

Line 1: Define local variables:

• a, op, b - comparison operands and operator, i.e., "3.6" > "3.5a".
• al, bl - letter tails of a and b, initialized to the tail item, i.e., "6" and "5a".

Lines 2, 3: Left-trim digits from the tail items so only letters are left, if any, i.e., "" and "a".

Line 4: Right trim letters from a and b to leave just the sequence of numeric items as local variables ai and bi, i.e., "3.6" and "3.5". Notable example: "4.01-RC2" > "4.01-RC1" yields ai="4.01" al="-RC2" and bi="4.01" bl="-RC1".

Line 6: Define local variables:

• ap, bp - zero right-paddings for ai and bi. Start by keeping the inter-item dots only, of which number equals the number of elements of a and b respectively.

Line 7: Then append "0" after each dot to make padding masks.

Line 9: Local variables:

• w - item width
• fmt - printf format string, to be calculated
• x - temporary
• With IFS=. bash splits variable values at '.'.

Line 10: Calculate w, the maximum item width, which will be used to align items for lexicographic comparison. In our example w=2.

Line 11: Create the printf alignment format by replacing each character of $a.$b with %${w}s, i.e., "3.6" > "3.5a" yields "%2s%2s%2s%2s".

Line 12: "printf -v a" sets the value of variable a. This is equivalent to a=sprintf(...) in many programming languages. Note that here, by effect of IFS=. the arguments to printf split into individual items.

With the first printf items of a are left-padded with spaces while enough "0" items are appended from bp to ensure that the resulting string a can be meaningfully compared to a similarly formatted b.

Note that we append bp - not ap to ai because ap and bp may have different lenghts, so this results in a and b having equal lengths.

With the second printf we append the letter part al to a with enough padding to enable meaningful comparison. Now a is ready for comparison with b.

Line 13: Same as line 12 but for b.

Line 15: Split comparison cases between non-built-in (<= and >=) and built-in operators.

Line 16: If the comparison operator is <= then test for a<b or a=b - respectively >= a<b or a=b

Line 17: Test for built-in comparison operators.

<>

# All tests

function P { printf "$@"; }
function EXPECT { printf "$@"; }
function CODE { awk $BASH_LINENO'==NR{print " "$2,$3,$4}' "$0"; }
P 'Note: ++ (true) and __ (false) mean that V works correctly.\n'

V 2.5    '!='  2.5      && P + || P _; EXPECT _; CODE
V 2.5    '='   2.5      && P + || P _; EXPECT +; CODE
V 2.5    '=='  2.5      && P + || P _; EXPECT +; CODE

V 2.5a   '=='  2.5b     && P + || P _; EXPECT _; CODE
V 2.5a   '<'   2.5b     && P + || P _; EXPECT +; CODE
V 2.5a   '>'   2.5b     && P + || P _; EXPECT _; CODE
V 2.5b   '>'   2.5a     && P + || P _; EXPECT +; CODE
V 2.5b   '<'   2.5a     && P + || P _; EXPECT _; CODE
V 3.5    '<'   3.5b     && P + || P _; EXPECT +; CODE
V 3.5    '>'   3.5b     && P + || P _; EXPECT _; CODE
V 3.5b   '>'   3.5      && P + || P _; EXPECT +; CODE
V 3.5b   '<'   3.5      && P + || P _; EXPECT _; CODE
V 3.6    '<'   3.5b     && P + || P _; EXPECT _; CODE
V 3.6    '>'   3.5b     && P + || P _; EXPECT +; CODE
V 3.5b   '<'   3.6      && P + || P _; EXPECT +; CODE
V 3.5b   '>'   3.6      && P + || P _; EXPECT _; CODE

V 2.5.7  '<='  2.5.6    && P + || P _; EXPECT _; CODE
V 2.4.10 '<'   2.4.9    && P + || P _; EXPECT _; CODE
V 2.4.10 '<'   2.5.9    && P + || P _; EXPECT +; CODE
V 3.4.10 '<'   2.5.9    && P + || P _; EXPECT _; CODE
V 2.4.8  '>'   2.4.10   && P + || P _; EXPECT _; CODE
V 2.5.6  '<='  2.5.6    && P + || P _; EXPECT +; CODE
V 2.5.6  '>='  2.5.6    && P + || P _; EXPECT +; CODE
V 3.0    '<'   3.0.3    && P + || P _; EXPECT +; CODE
V 3.0002 '<'   3.0003.3 && P + || P _; EXPECT +; CODE
V 3.0002 '>'   3.0003.3 && P + || P _; EXPECT _; CODE
V 3.0003.3 '<' 3.0002   && P + || P _; EXPECT _; CODE
V 3.0003.3 '>' 3.0002   && P + || P _; EXPECT +; CODE

V 4.0-RC2 '>' 4.0-RC1   && P + || P _; EXPECT +; CODE
V 4.0-RC2 '<' 4.0-RC1   && P + || P _; EXPECT _; CODE

if it's just about to know whether one version is lower than another I came up checking whether sort --version-sort changes the order of my version strings:

    string="$1
$2"
    [ "$string" == "$(sort --version-sort <<< "$string")" ]

I implemented a function that returns the same results as Dennis Williamson's but uses fewer lines. It does perform a sanity check initially which causes 1..0 to fail from his tests (which I would argue should be the case) but all of his other tests pass with this code:

#!/bin/bash
version_compare() {
    if [[ $1 =~ ^([0-9]+\.?)+$ && $2 =~ ^([0-9]+\.?)+$ ]]; then
        local l=(${1//./ }) r=(${2//./ }) s=${#l[@]}; [[ ${#r[@]} -gt ${#l[@]} ]] && s=${#r[@]}

        for i in $(seq 0 $((s - 1))); do
            [[ ${l[$i]} -gt ${r[$i]} ]] && return 1
            [[ ${l[$i]} -lt ${r[$i]} ]] && return 2
        done

        return 0
    else
        echo "Invalid version number given"
        exit 1
    fi
}

Here is a simple Bash function that uses no external commands. It works for version strings that have up to three numeric parts in them - less than 3 is fine as well. It can easily be extended for more. It implements =, <, <=, >, >=, and != conditions.

#!/bin/bash
vercmp() {
    version1=$1 version2=$2 condition=$3
    
    IFS=. v1_array=($version1) v2_array=($version2)
    v1=$((v1_array[0] * 100 + v1_array[1] * 10 + v1_array[2]))
    v2=$((v2_array[0] * 100 + v2_array[1] * 10 + v2_array[2]))
    diff=$((v2 - v1))
    [[ $condition = '='  ]] && ((diff == 0)) && return 0
    [[ $condition = '!=' ]] && ((diff != 0)) && return 0
    [[ $condition = '<'  ]] && ((diff >  0)) && return 0
    [[ $condition = '<=' ]] && ((diff >= 0)) && return 0
    [[ $condition = '>'  ]] && ((diff <  0)) && return 0
    [[ $condition = '>=' ]] && ((diff <= 0)) && return 0
    return 1
}

Here is the test:

for tv1 in '*' 1.1.1 2.5.3 7.3.0 0.5.7 10.3.9 8.55.32 0.0.1; do
    for tv2 in 3.1.1 1.5.3 4.3.0 0.0.7 0.3.9 11.55.32 10.0.0 '*'; do
      for c in '=' '>' '<' '>=' '<=' '!='; do
        vercmp "$tv1" "$tv2" "$c" && printf '%s\n' "$tv1 $c $tv2 is true" || printf '%s\n' "$tv1 $c $tv2 is false"
      done
    done
done

A subset of the test output:

<snip>

* >= * is true
* <= * is true
* != * is true
1.1.1 = 3.1.1 is false
1.1.1 > 3.1.1 is false
1.1.1 < 3.1.1 is true
1.1.1 >= 3.1.1 is false
1.1.1 <= 3.1.1 is true
1.1.1 != 3.1.1 is true
1.1.1 = 1.5.3 is false
1.1.1 > 1.5.3 is false
1.1.1 < 1.5.3 is true
1.1.1 >= 1.5.3 is false
1.1.1 <= 1.5.3 is true
1.1.1 != 1.5.3 is true
1.1.1 = 4.3.0 is false
1.1.1 > 4.3.0 is false

<snip>

$ for OVFTOOL_VERSION in "4.2.0" "4.2.1" "5.2.0" "3.2.0" "4.1.9" "4.0.1" "4.3.0" "4.5.0" "4.2.1" "30.1.0" "4" "5" "4.1" "4.3"
> do
>   if [ $(echo "$OVFTOOL_VERSION 4.2.0" | tr " " "\n" | sort --version-sort | head -n 1) = 4.2.0 ]; then 
>     echo "$OVFTOOL_VERSION is >= 4.2.0"; 
>   else 
>     echo "$OVFTOOL_VERSION is < 4.2.0"; 
>   fi
> done
4.2.0 is >= 4.2.0
4.2.1 is >= 4.2.0
5.2.0 is >= 4.2.0
3.2.0 is < 4.2.0
4.1.9 is < 4.2.0
4.0.1 is < 4.2.0
4.3.0 is >= 4.2.0
4.5.0 is >= 4.2.0
4.2.1 is >= 4.2.0
30.1.0 is >= 4.2.0
4 is < 4.2.0
5 is >= 4.2.0
4.1 is < 4.2.0
4.3 is >= 4.2.0

This is also a pure bash solution, as printf is a bash builtin.

function ver()
# Description: use for comparisons of version strings.
# $1  : a version string of form 1.2.3.4
# use: (( $(ver 1.2.3.4) >= $(ver 1.2.3.3) )) && echo "yes" || echo "no"
{
    printf "%02d%02d%02d%02d" ${1//./ }
}

I'm using embedded Linux (Yocto) with BusyBox. BusyBox sort doesn't have a -V option (but BusyBox expr match can do regular expressions). So I needed a Bash version compare which worked with that constraint.

I've made the following (similar to Dennis Williamson's answer) to compare using a "natural sort" type of algorithm. It splits the string into numeric parts and non-numeric parts; it compares the numeric parts numerically (so 10 is greater than 9), and compares the non-numeric parts as a plain ASCII comparison.

ascii_frag() {
	expr match "$1" "\([^[:digit:]]*\)"
}

ascii_remainder() {
	expr match "$1" "[^[:digit:]]*\(.*\)"
}

numeric_frag() {
	expr match "$1" "\([[:digit:]]*\)"
}

numeric_remainder() {
	expr match "$1" "[[:digit:]]*\(.*\)"
}

vercomp_debug() {
	OUT="$1"
	#echo "${OUT}"
}

# return 1 for $1 > $2
# return 2 for $1 < $2
# return 0 for equal
vercomp() {
	local WORK1="$1"
	local WORK2="$2"
	local NUM1="", NUM2="", ASCII1="", ASCII2=""
	while true; do
		vercomp_debug "ASCII compare"
		ASCII1=`ascii_frag "${WORK1}"`
		ASCII2=`ascii_frag "${WORK2}"`
		WORK1=`ascii_remainder "${WORK1}"`
		WORK2=`ascii_remainder "${WORK2}"`
		vercomp_debug "\"${ASCII1}\" remainder \"${WORK1}\""
		vercomp_debug "\"${ASCII2}\" remainder \"${WORK2}\""

		if [ "${ASCII1}" \> "${ASCII2}" ]; then
			vercomp_debug "ascii ${ASCII1} > ${ASCII2}"
			return 1
		elif [ "${ASCII1}" \< "${ASCII2}" ]; then
			vercomp_debug "ascii ${ASCII1} < ${ASCII2}"
			return 2
		fi
		vercomp_debug "--------"

		vercomp_debug "Numeric compare"
		NUM1=`numeric_frag "${WORK1}"`
		NUM2=`numeric_frag "${WORK2}"`
		WORK1=`numeric_remainder "${WORK1}"`
		WORK2=`numeric_remainder "${WORK2}"`
		vercomp_debug "\"${NUM1}\" remainder \"${WORK1}\""
		vercomp_debug "\"${NUM2}\" remainder \"${WORK2}\""

		if [ -z "${NUM1}" -a -z "${NUM2}" ]; then
			vercomp_debug "blank 1 and blank 2 equal"
			return 0
		elif [ -z "${NUM1}" -a -n "${NUM2}" ]; then
			vercomp_debug "blank 1 less than non-blank 2"
			return 2
		elif [ -n "${NUM1}" -a -z "${NUM2}" ]; then
			vercomp_debug "non-blank 1 greater than blank 2"
			return 1
		fi

		if [ "${NUM1}" -gt "${NUM2}" ]; then
			vercomp_debug "num ${NUM1} > ${NUM2}"
			return 1
		elif [ "${NUM1}" -lt "${NUM2}" ]; then
			vercomp_debug "num ${NUM1} < ${NUM2}"
			return 2
		fi
		vercomp_debug "--------"
	done
}

It can compare more complicated version numbers such as

• 1.2-r3 versus 1.2-r4
• 1.2rc3 versus 1.2r4

Note that it doesn't return the same result for some of the corner-cases in Dennis Williamson's answer. In particular:

1            1.0          <
1.0          1            >
1.0.2.0      1.0.2        >
1..0         1.0          >
1.0          1..0         <

But those are corner cases, and I think the results are still reasonable.

Here's a pure Bash solution that supports revisions (e.g. '1.0-r1'), based on the answer posted by Dennis Williamson. It can easily be modified to support stuff like '-RC1' or extract the version from a more complex string by changing the regular expression.

For details regarding the implementation, please refer to in-code comments and/or enable the included debug code:

#!/bin/bash

# Compare two version strings [$1: version string 1 (v1), $2: version string 2 (v2)]
# Return values:
#   0: v1 == v2
#   1: v1 > v2
#   2: v1 < v2
# Based on: https://stackoverflow.com/a/4025065 by Dennis Williamson
function compare_versions() {

    # Trivial v1 == v2 test based on string comparison
    [[ "$1" == "$2" ]] && return 0

    # Local variables
    local regex="^(.*)-r([0-9]*)$" va1=() vr1=0 va2=() vr2=0 len i IFS="."

    # Split version strings into arrays, extract trailing revisions
    if [[ "$1" =~ ${regex} ]]; then
        va1=(${BASH_REMATCH[1]})
        [[ -n "${BASH_REMATCH[2]}" ]] && vr1=${BASH_REMATCH[2]}
    else
        va1=($1)
    fi
    if [[ "$2" =~ ${regex} ]]; then
        va2=(${BASH_REMATCH[1]})
        [[ -n "${BASH_REMATCH[2]}" ]] && vr2=${BASH_REMATCH[2]}
    else
        va2=($2)
    fi

    # Bring va1 and va2 to same length by filling empty fields with zeros
    (( ${#va1[@]} > ${#va2[@]} )) && len=${#va1[@]} || len=${#va2[@]}
    for ((i=0; i < len; ++i)); do
        [[ -z "${va1[i]}" ]] && va1[i]="0"
        [[ -z "${va2[i]}" ]] && va2[i]="0"
    done

    # Append revisions, increment length
    va1+=($vr1)
    va2+=($vr2)
    len=$((len+1))

    # *** DEBUG ***
    #echo "TEST: '${va1[@]} (?) ${va2[@]}'"

    # Compare version elements, check if v1 > v2 or v1 < v2
    for ((i=0; i < len; ++i)); do
        if (( 10#${va1[i]} > 10#${va2[i]} )); then
            return 1
        elif (( 10#${va1[i]} < 10#${va2[i]} )); then
            return 2
        fi
    done

    # All elements are equal, thus v1 == v2
    return 0
}


# ---------- everything below this line is just for testing ----------


# Test compare_versions [$1: version string 1, $2: version string 2, $3: expected result]
function test_compare_versions() {
    local op
    compare_versions "$1" "$2"
    case $? in
        0) op="==" ;;
        1) op=">" ;;
        2) op="<" ;;
    esac
    if [[ "$op" == "$3" ]]; then
        echo -e "\e[1;32mPASS: '$1 $op $2'\e[0m"
    else
        echo -e "\e[1;31mFAIL: '$1 $3 $2' (result: '$1 $op $2')\e[0m"
    fi
}

echo -e "\nThe following tests should pass:"
while read -r test; do
    test_compare_versions $test
done << EOF
1            1            ==
2.1          2.2          <
3.0.4.10     3.0.4.2      >
4.08         4.08.01      <
3.2.1.9.8144 3.2          >
3.2          3.2.1.9.8144 <
1.2          2.1          <
2.1          1.2          >
5.6.7        5.6.7        ==
1.01.1       1.1.1        ==
1.1.1        1.01.1       ==
1            1.0          ==
1.0          1            ==
1.0.2.0      1.0.2        ==
1..0         1.0          ==
1.0          1..0         ==
1.0-r1       1.0-r3       <
1.0-r9       2.0          <
3.0-r15      3.0-r9       >
...-r1       ...-r2       <
2.0-r1       1.9.8.21-r2  >
1.0          3.8.9.32-r   <
-r           -r3          <
-r3          -r           >
-r3          -r3          ==
-r           -r           ==
0.0-r2       0.0.0.0-r2   ==
1.0.0.0-r2   1.0-r2       ==
0.0.0.1-r7   -r9          >
0.0-r0       0            ==
1.002.0-r6   1.2.0-r7     <
001.001-r2   1.1-r2       ==
5.6.1-r0     5.6.1        ==
EOF

echo -e "\nThe following tests should fail:"
while read -r test; do
    test_compare_versions $test
done << EOF
1            1            >
3.0.5-r5     3..5-r5      >
4.9.21-r3    4.8.22-r9    <
1.0-r        1.0-r1       ==
-r           1.0-r        >
-r1          0.0-r1       <
-r2          0-r2         <
EOF

For old version/busybox sort. Simple form provide roughly result and often works.

sort -n

This is escpecial useful on version which contains alpha symbols like

10.c.3
10.a.4
2.b.5

Here's a refinement of the top answer (Dennis's) that is more concise and uses a different return value scheme to make it easy to implement <= and >= with a single comparison. It also compares everything after the first character not in [0-9.] lexicographically, so 1.0rc1 < 1.0rc2.

# Compares two tuple-based, dot-delimited version numbers a and b (possibly
# with arbitrary string suffixes). Returns:
# 1 if a<b
# 2 if equal
# 3 if a>b
# Everything after the first character not in [0-9.] is compared
# lexicographically using ASCII ordering if the tuple-based versions are equal.
compare_versions() {
    if [[ $1 == "$2" ]]; then
        return 2
    fi
    local IFS=.
    local i a=(${1%%[^0-9.]*}) b=(${2%%[^0-9.]*})
    local arem=${1#${1%%[^0-9.]*}} brem=${2#${2%%[^0-9.]*}}
    for ((i=0; i<${#a[@]} || i<${#b[@]}; i++)); do
        if ((10#${a[i]:-0} < 10#${b[i]:-0})); then
            return 1
        elif ((10#${a[i]:-0} > 10#${b[i]:-0})); then
            return 3
        fi
    done
    if [ "$arem" '<' "$brem" ]; then
        return 1
    elif [ "$arem" '>' "$brem" ]; then
        return 3
    fi
    return 2
}

To address @gammazero's comment, a longer version that (I think) is compatible with semantic versioning is this:

# Compares two dot-delimited decimal-element version numbers a and b that may
# also have arbitrary string suffixes. Compatible with semantic versioning, but
# not as strict: comparisons of non-semver strings may have unexpected
# behavior.
#
# Returns:
# 1 if a<b
# 2 if equal
# 3 if a>b
compare_versions() {
    local LC_ALL=C

    # Optimization
    if [[ $1 == "$2" ]]; then
        return 2
    fi

    # Compare numeric release versions. Supports an arbitrary number of numeric
    # elements (i.e., not just X.Y.Z) in which unspecified indices are regarded
    # as 0.
    local aver=${1%%[^0-9.]*} bver=${2%%[^0-9.]*}
    local arem=${1#$aver} brem=${2#$bver}
    local IFS=.
    local i a=($aver) b=($bver)
    for ((i=0; i<${#a[@]} || i<${#b[@]}; i++)); do
        if ((10#${a[i]:-0} < 10#${b[i]:-0})); then
            return 1
        elif ((10#${a[i]:-0} > 10#${b[i]:-0})); then
            return 3
        fi
    done

    # Remove build metadata before remaining comparison
    arem=${arem%%+*}
    brem=${brem%%+*}

    # Prelease (w/remainder) always older than release (no remainder)
    if [ -n "$arem" -a -z "$brem" ]; then
        return 1
    elif [ -z "$arem" -a -n "$brem" ]; then
        return 3
    fi

    # Otherwise, split by periods and compare individual elements either
    # numerically or lexicographically
    local a=(${arem#-}) b=(${brem#-})
    for ((i=0; i<${#a[@]} && i<${#b[@]}; i++)); do
        local anns=${a[i]#${a[i]%%[^0-9]*}} bnns=${b[i]#${b[i]%%[^0-9]*}}
        if [ -z "$anns$bnns" ]; then
            # Both numeric
            if ((10#${a[i]:-0} < 10#${b[i]:-0})); then
                return 1
            elif ((10#${a[i]:-0} > 10#${b[i]:-0})); then
                return 3
            fi
        elif [ -z "$anns" ]; then
            # Numeric comes before non-numeric
            return 1
        elif [ -z "$bnns" ]; then
            # Numeric comes before non-numeric
            return 3
        else
            # Compare lexicographically
            if [[ ${a[i]} < ${b[i]} ]]; then
                return 1
            elif [[ ${a[i]} > ${b[i]} ]]; then
                return 3
            fi
        fi
    done

    # Fewer elements is earlier
    if (( ${#a[@]} < ${#b[@]} )); then
        return 1
    elif (( ${#a[@]} > ${#b[@]} )); then
        return 3
    fi

    # Must be equal!
    return 2
}

You all gave complicated solutions. Here's a simpler one.

function compare_versions {
    local a=${1%%.*} b=${2%%.*}
    [[ "10#${a:-0}" -gt "10#${b:-0}" ]] && return 1
    [[ "10#${a:-0}" -lt "10#${b:-0}" ]] && return 2
    a=${1:${#a} + 1} b=${2:${#b} + 1}
    [[ -z $a && -z $b ]] || compare_versions "$a" "$b"
}

Usage: compare_versions <ver_a> <ver_b>

Return code 1 means first version is greater than second, 2 means less, and 0 means both are equal.

---

Also a non-recursive version:

function compare_versions {
	local a=$1 b=$2 x y

	while [[ $a || $b ]]; do
		x=${a%%.*} y=${b%%.*}
		[[ "10#${x:-0}" -gt "10#${y:-0}" ]] && return 1
		[[ "10#${x:-0}" -lt "10#${y:-0}" ]] && return 2
		a=${a:${#x} + 1} b=${b:${#y} + 1}
	done

	return 0
}

How about this? Seems to work?

checkVersion() {
subVer1=$1
subVer2=$2

[ "$subVer1" == "$subVer2" ] && echo "Version is same"
echo "Version 1 is $subVer1"
testVer1=$subVer1
echo "Test version 1 is $testVer1"
x=0
while [[ $testVer1 != "" ]]
do
  ((x++))
  testVer1=`echo $subVer1|cut -d "." -f $x`
  echo "testVer1 now is $testVer1"
  testVer2=`echo $subVer2|cut -d "." -f $x`
  echo "testVer2 now is $testVer2"
  if [[ $testVer1 -gt $testVer2 ]]
  then
    echo "$ver1 is greater than $ver2"
    break
  elif [[ "$testVer2" -gt "$testVer1" ]]
  then
    echo "$ver2 is greater than $ver1"
    break
  fi
  echo "This is the sub verion for first value $testVer1"
  echo "This is the sub verion for second value $testVer2"
done
}

ver1=$1
ver2=$2
checkVersion "$ver1" "$ver2"

Here is another pure bash solution without any external calls:

#!/bin/bash

function version_compare {

IFS='.' read -ra ver1 <<< "$1"
IFS='.' read -ra ver2 <<< "$2"

[[ ${#ver1[@]} -gt ${#ver2[@]} ]] && till=${#ver1[@]} || till=${#ver2[@]}

for ((i=0; i<${till}; i++)); do

    local num1; local num2;

    [[ -z ${ver1[i]} ]] && num1=0 || num1=${ver1[i]}
    [[ -z ${ver2[i]} ]] && num2=0 || num2=${ver2[i]}

    if [[ $num1 -gt $num2 ]]; then
        echo ">"; return 0
    elif
       [[ $num1 -lt $num2 ]]; then
        echo "<"; return 0
    fi
done

echo "="; return 0
}

echo "${1} $(version_compare "${1}" "${2}") ${2}"

And there is even more simple solution, if you are sure that the versions in question do not contain leading zeros after the first dot:

#!/bin/bash

function version_compare {

local ver1=${1//.}
local ver2=${2//.}


    if [[ $ver1 -gt $ver2 ]]; then
        echo ">"; return 0
    elif    
       [[ $ver1 -lt $ver2 ]]; then
        echo "<"; return 0
    fi 

echo "="; return 0
}

echo "${1} $(version_compare "${1}" "${2}") ${2}"

This will work for something like 1.2.3 vs 1.3.1 vs 0.9.7, but won't work with 1.2.3 vs 1.2.3.0 or 1.01.1 vs 1.1.1

I implemented yet another comparator function. This one had two specific requirements: (i) I didn't want the function to fail by using return 1 but echo instead; (ii) as we're retrieving versions from a git repository version "1.0" should be bigger than "1.0.2", meaning that "1.0" comes from trunk.

function version_compare {
  IFS="." read -a v_a <<< "$1"
  IFS="." read -a v_b <<< "$2"

  while [[ -n "$v_a" || -n "$v_b" ]]; do
    [[ -z "$v_a" || "$v_a" -gt "$v_b" ]] && echo 1 && return
    [[ -z "$v_b" || "$v_b" -gt "$v_a" ]] && echo -1 && return

    v_a=("${v_a[@]:1}")
    v_b=("${v_b[@]:1}")
  done

  echo 0
}

Feel free to comment and suggest improvements.

You can use version CLI to check version's constraints

$ version ">=1.0, <2.0" "1.7"
$ go version | version ">=1.9"

Bash script example:

#!/bin/bash

if `version -b ">=9.0.0" "$(gcc --version)"`; then
  echo "gcc version satisfies constraints >=9.0.0"
else
  echo "gcc version doesn't satisfies constraints >=9.0.0"
fi

Wow... this is way down the list of an old question, but I think this is a pretty elegant answer. First convert each dot-separated version into its own array, using shell parameter expansion (See Shell Parameter Expansion).

v1="05.2.3"     # some evil examples that work here
v2="7.001.0.0"

declare -a v1_array=(${v1//./ })
declare -a v2_array=(${v2//./ })

Now the two arrays have the version number as a numerical string in priority order. Lots of the above solutions take you from there, but it all derives from the observation that version string is just an integer with an arbitrary base. We can test finding the first unequal digit (like strcmp does for characters in a string).

compare_version() {
  declare -a v1_array=(${1//./ })
  declare -a v2_array=(${2//./ })

  while [[ -nz $v1_array ]] || [[ -nz $v2_array ]]; do
    let v1_val=${v1_array:-0}  # this will remove any leading zeros
    let v2_val=${v2_array:-0}
    let result=$((v1_val-v2_val))

    if (( result != 0 )); then
      echo $result
      return
    fi

    v1_array=("${v1_array[@]:1}") # trim off the first "digit". it doesn't help
    v2_array=("${v2_array[@]:1}")
  done

  # if we get here, both the arrays are empty and neither has been numerically
  # different, which is equivalent to the two versions being equal

  echo 0
  return
}

This echoes a negative number if the first version is less than the second, a zero if they're equal and a positive number if the first version is greater. Some output:

$ compare_version 1 1.2
-2
$ compare_version "05.1.3" "5.001.03.0.0.0.1"
-1
$ compare_version "05.1.3" "5.001.03.0.0.0"
0
$ compare_version "05.1.3" "5.001.03.0"
0
$ compare_version "05.1.3" "5.001.30.0"
-27
$ compare_version "05.2.3" "7.001.0.0"
-2
$ compare_version "05.1.3" "5.001.30.0"
-27
$ compare_version "7.001.0.0" "05.1.3"
2

Degenerate cases like, ".2" or "3.0." don't work (undefined results), and if non-numeric characters are present beside the '.' it might fail (haven't tested) but will certainly be undefined. So this should be paired with a sanitizing function or appropriate check for valid formatting. Also, I'm sure with some tweaking, this could be made more robust without too much extra baggage.

ver_cmp()
{
    local IFS=.
    local V1=($1) V2=($2) I
    for ((I=0 ; I<${#V1[*]} || I<${#V2[*]} ; I++)) ; do
        [[ ${V1[$I]:-0} -lt ${V2[$I]:-0} ]] && echo -1 && return
        [[ ${V1[$I]:-0} -gt ${V2[$I]:-0} ]] && echo 1 && return
    done
    echo 0
}

ver_eq()
{
    [[ $(ver_cmp "$1" "$2") -eq 0 ]]
}

ver_lt()
{
    [[ $(ver_cmp "$1" "$2") -eq -1 ]]
}

ver_gt()
{
    [[ $(ver_cmp "$1" "$2") -eq 1 ]]
}

ver_le()
{
    [[ ! $(ver_cmp "$1" "$2") -eq 1 ]]
}

ver_ge()
{
    [[ ! $(ver_cmp "$1" "$2") -eq -1 ]]
}

To test:

( ( while read V1 V2 ; do echo $V1 $(ver_cmp $V1 $V2) $V2 ; done ) <<EOF
1.2.3 2.2.3
2.2.3 2.2.2
3.10 3.2
2.2 2.2.1
3.1 3.1.0
EOF
) | sed 's/ -1 / < / ; s/ 0 / = / ; s/ 1 / > /' | column -t

1.2.3  <  2.2.3
2.2.3  >  2.2.2
3.10   >  3.2
2.2    <  2.2.1
3.1    =  3.1.0


ver_lt 10.1.2 10.1.20 && echo 'Your version is too old'

Your version is too old

I came across and solved this problem, to add an additional (and shorter and simpler) answer...

First note, extended shell comparison failed as you may already know...

    if [[ 1.2.0 < 1.12.12 ]]; then echo true; else echo false; fi
    false

Using the sort -t'.'-g (or sort -V as mentioned by kanaka) to order versions and simple bash string comparison I found a solution. The input file contains versions in columns 3 and 4 which I want to compare. This iterates through the list identifying a match or if one is greater than the other. Hope this may still help anyone looking to do this using bash as simple as possible.

while read l
do
    #Field 3 contains version on left to compare (change -f3 to required column).
    kf=$(echo $l | cut -d ' ' -f3)
    #Field 4 contains version on right to compare (change -f4 to required column).
    mp=$(echo $l | cut -d ' ' -f4)

    echo 'kf = '$kf
    echo 'mp = '$mp

    #To compare versions m.m.m the two can be listed and sorted with a . separator and the greater version found.
    gv=$(echo -e $kf'\n'$mp | sort -t'.' -g | tail -n 1)

    if [ $kf = $mp ]; then 
        echo 'Match Found: '$l
    elif [ $kf = $gv ]; then
        echo 'Karaf feature file version is greater '$l
    elif [ $mp = $gv ]; then
        echo 'Maven pom file version is greater '$l
   else
       echo 'Comparison error '$l
   fi
done < features_and_pom_versions.tmp.txt

Thanks to Barry's blog for the sort idea... ref: http://bkhome.org/blog/?viewDetailed=02199

### the answer is does we second argument is higher
function _ver_higher {
        ver=`echo -ne "$1\n$2" |sort -Vr |head -n1`
        if [ "$2" == "$1" ]; then
                return 1
        elif [ "$2" == "$ver" ]; then
                return 0
        else
                return 1
        fi
}

if _ver_higher $1 $2; then
        echo higher
else
        echo same or less
fi

It's pretty simple and small.

Thanks to Dennis's solution, we can extend it to allow comparison operators '>', '<', '=', '==', '<=', and '>='.

# compver ver1 '=|==|>|<|>=|<=' ver2
compver() { 
    local op
    vercomp $1 $3
    case $? in
        0) op='=';;
        1) op='>';;
        2) op='<';;
    esac
    [[ $2 == *$op* ]] && return 0 || return 1
}

We can then use comparison operators in the expressions like:

compver 1.7 '<=' 1.8
compver 1.7 '==' 1.7
compver 1.7 '=' 1.7

and test only the true/false of the result, like:

if compver $ver1 '>' $ver2; then
    echo "Newer"
fi

Here's another pure bash version, rather smaller than the accepted answer. It only checks whether a version is less than or equal to a "minimum version", and it will check alphanumeric sequences lexicographically, which often gives the wrong result ("snapshot" is not later than "release", to give a common example). It will work fine for major/minor.

is_number() {
	case "$BASH_VERSION" in
		3.1.*)
			PATTERN='\^\[0-9\]+\$'
			;;
		*)
			PATTERN='^[0-9]+$'
			;;
	esac

	[[ "$1" =~ $PATTERN ]]
}

min_version() {
	if [[ $# != 2 ]]
	then
		echo "Usage: min_version current minimum"
		return
	fi

	A="${1%%.*}"
	B="${2%%.*}"

	if [[ "$A" != "$1" && "$B" != "$2" && "$A" == "$B" ]]
	then
		min_version "${1#*.}" "${2#*.}"
	else
		if is_number "$A" && is_number "$B"
		then
			[[ "$A" -ge "$B" ]]
		else
			[[ ! "$A" < "$B" ]]
		fi
	fi
}

Another approach(modified version of @joynes) that compares dotted versions as asked in the question
(i.e "1.2", "2.3.4", "1.0", "1.10.1", etc.).
The maximum number of positions has to be known in advance. The approach expects max 3 version positions.

expr $(printf "$1\n$2" | sort -t '.' -k 1,1 -k 2,2 -k 3,3 -g | sed -n 2p) != $2

example usage:

expr $(printf "1.10.1\n1.7" | sort -t '.' -k 1,1 -k 2,2 -k 3,3 -g | sed -n 2p) != "1.7"

returns: 1 since 1.10.1 is bigger than 1.7

expr $(printf "1.10.1\n1.11" | sort -t '.' -k 1,1 -k 2,2 -k 3,3 -g | sed -n 2p) != "1.11"

returns: 0 since 1.10.1 is lower than 1.11

function version_compare () {
  function sub_ver () {
    local len=${#1}
    temp=${1%%"."*} && indexOf=`echo ${1%%"."*} | echo ${#temp}`
    echo -e "${1:0:indexOf}"
  }
  function cut_dot () {
    local offset=${#1}
    local length=${#2}
    echo -e "${2:((++offset)):length}"
  }
  if [ -z "$1" ] || [ -z "$2" ]; then
    echo "=" && exit 0
  fi
  local v1=`echo -e "${1}" | tr -d '[[:space:]]'`
  local v2=`echo -e "${2}" | tr -d '[[:space:]]'`
  local v1_sub=`sub_ver $v1`
  local v2_sub=`sub_ver $v2`
  if (( v1_sub > v2_sub )); then
    echo ">"
  elif (( v1_sub < v2_sub )); then
    echo "<"
  else
    version_compare `cut_dot $v1_sub $v1` `cut_dot $v2_sub $v2`
  fi
}

### Usage:

version_compare "1.2.3" "1.2.4"
# Output: <

Credit goes to @Shellman

I didn't like any of these solutions because they're buggy, non-portable, etc.

My (current) effort to produce a better solution... src:version_compare(), tests

Sorta-copied/Pasted here...

Source:

##
# Compare two versions.
#
# **Usage:** version_compare version1 operator version2
#
# - operator:
#
#   + ``lesser_than``, ``-lt``, ``<``
#   + ``lesser_than_or_equal``, ``-le``, ``<=``
#   + ``greater_than``, ``-gt``, ``>``
#   + ``greater_than_or_equal``, ``-ge``, ``>=``
#   + ``equal``, ``-eq``, ``==``
#   + ``not_equal``, ``-ne``, ``!=``
#
# - version{1,2}: arbitrary version strings to compare
#
# **Version Format:** ``[0-9]+($VERSION_SEPARATOR[0-9]+)*`` (i.e. 1, 1.0, 90, 1.2.3.4)
#
# **Returns:** true if comparison statement is correct
##
version_compare() {
	_largest_version "$1" "$3"; _cmp="$(printf '%s' "$?")"

	# Check for valid responses or bail early
	case "$_cmp" in
		1|0|2) :;;
		*) _die "$_cmp" 'version comparison failed';;
	esac

	# The easy part
	case "$2" in
		'lesser_than'|'-lt'|'<')
			[ "$_cmp" = '2' ] && return 0
			;;
		'lesser_or_equal'|'-le'|'<=')
			[ "$_cmp" = '0' ] && return 0
			[ "$_cmp" = '2' ] && return 0
			;;
		'greater_than'|'-gt'|'>')
			[ "$_cmp" = '1' ] && return 0
			;;
		'greater_or_equal'|'-ge'|'>=')
			[ "$_cmp" = '1' ] && return 0
			[ "$_cmp" = '0' ] && return 0
			;;
		'equal'|'-eq'|'==')
			[ "$_cmp" = '0' ] && return 0
			;;
		'not_equal'|'-ne'|'!=')
			[ "$_cmp" = '1' ] && return 0
			[ "$_cmp" = '2' ] && return 0
			;;
		*) _die 7 'Unknown operatoration called for version_compare().';;
	esac
	return 1
}

##
# Print a formatted (critical) message and exit with status.
#
# **Usage:** _die [exit_status] message
#
# - exit_status: exit code to use with script termination (default: 1)
# - message: message to print before terminating script execution
##
_die() {
        # If first argument was an integer, use as exit_status
        if [ "$1" -eq "$1" ] 2>/dev/null; then
                _exit_status="$1"; shift
        else
                _exit_status=1
        fi

        printf '*** CRITICAL: %s ***\n' "$1"
        exit "$_exit_status"
}

##
# Compare two versions.
# Check if one version is larger/smaller/equal than/to another.
#
# **Usage:** _largest_version ver1 ver2
#
# Returns: ($1 > $2): 1 ; ($1 = $2): 0 ; ($1 < $2): 2
# [IOW- 1 = $1 is largest; 0 = neither ; 2 = $2 is largest]
##
_largest_version() (
	# Value used to separate version components
	VERSION_SEPARATOR="${VERSION_SEPARATOR:-.}"

	for _p in "$1" "$2"; do
		[ "$(printf %.1s "$_p")" = "$VERSION_SEPARATOR" ] &&
			_die 7 'invalid version pattern provided'
	done

	# Split versions on VER_SEP into int/sub
	_v="$1$2"
	_v1="$1"
	_s1="${1#*$VERSION_SEPARATOR}"
	if [ "$_v1" = "$_s1" ]; then
		_s1=''
		_m1="$_v1"
	else
		_m1="${1%%$VERSION_SEPARATOR*}"
	fi
	_v2="$2"
	_s2="${2#*$VERSION_SEPARATOR}"
	if [ "$_v2" = "$_s2" ]; then
		_s2=''
		_m2="$_v2"
	else
		_m2="${2%%$VERSION_SEPARATOR*}"
	fi

	# Both are equal
	[ "$_v1" = "$_v2" ] && return 0

	# Something is larger than nothing (30 < 30.0)
	if [ -n "$_v1" ] && [ ! -n "$_v2" ]; then
		return 1
	elif [ ! -n "$_v1" ] && [ -n "$_v2" ]; then
		return 2
	fi

	# Check for invalid
	case "$_m1$_m2" in
		*[!0-9]*)
			_die 7 'version_compare called with unsupported version type'
			;;
	esac

	# If a ver_sep is present
	if [ "${_v#*$VERSION_SEPARATOR}" != "$_v" ]; then
		# Check for a larger "major" version number
		[ "$_m1" -lt "$_m2" ] && return 2
		[ "$_m1" -gt "$_m2" ] && return 1

		# Compare substring components
		_largest_version "$_s1" "$_s2"; return "$?"
	else
		# Only integers present; simple integer comparison
		[ "$_v1" -lt "$_v2" ] && return 2
		[ "$_v1" -gt "$_v2" ] && return 1
	fi
)

Tests:

# Simple test of all operators
( version_compare '1' 'lesser_than' '2' ); [ "$?" = '0' ] || return 1
( version_compare '2' 'equal' '2' ); [ "$?" = '0' ] || return 1
( version_compare '3' 'not_equal' '1' ); [ "$?" = '0' ] || return 1
( version_compare '2' 'greater_than' '1' ); [ "$?" = '0' ] || return 1
( version_compare '1' '-lt' '2' ); [ "$?" = '0' ] || return 1
( version_compare '2' '-eq' '2' ); [ "$?" = '0' ] || return 1
( version_compare '3' '-ne' '1' ); [ "$?" = '0' ] || return 1
( version_compare '2' '-gt' '1' ); [ "$?" = '0' ] || return 1

# Semver test of primary operators (expect true)
( version_compare '7.0.1' '-lt' '7.0.2' ); [ "$?" = '0' ] || return 1
( version_compare '7.0.2' '-eq' '7.0.2' ); [ "$?" = '0' ] || return 1
( version_compare '3.0.2' '-ne' '2.0.7' ); [ "$?" = '0' ] || return 1
( version_compare '7.0.2' '-gt' '7.0.1' ); [ "$?" = '0' ] || return 1

# Semver test of primary operators (expect false)
( version_compare '7.0.2' '-lt' '7.0.1' ); [ "$?" = '1' ] || return 1
( version_compare '3.0.2' '-eq' '2.0.7' ); [ "$?" = '1' ] || return 1
( version_compare '7.0.2' '-ne' '7.0.2' ); [ "$?" = '1' ] || return 1
( version_compare '7.0.1' '-gt' '7.0.2' ); [ "$?" = '1' ] || return 1

# Mismatched version strings (expect true)
( version_compare '7' '-lt' '7.1' ); [ "$?" = '0' ] || return 1
( version_compare '3' '-ne' '7.0.0' ); [ "$?" = '0' ] || return 1
( version_compare '7.0.1' '-gt' '7' ); [ "$?" = '0' ] || return 1

# Mismatched version strings (expect false)
( version_compare '7.0.0' '-eq' '7.0' ); [ "$?" = '1' ] || return 1

# Invalid operation supplied
( version_compare '2' '-inv' '1' >/dev/null ); [ "$?" = '7' ] || return 1

# Invalid version formats
( version_compare '1..0' '==' '1.0' >/dev/null ); [ "$?" = '7' ] || return 1
( version_compare '1.0' '==' '1..0' >/dev/null ); [ "$?" = '7' ] || return 1
( version_compare '1.0' '==' '1.0b7' >/dev/null ); [ "$?" = '7' ] || return 1
( version_compare '1.0a' '==' '1.0' >/dev/null ); [ "$?" = '7' ] || return 1

# "how does that handle comparing 10.0.0 (not a number) to 2.0 (a number)?"
( version_compare '10.0.0' '-lt' '2.0' ); [ "$?" = '1' ] || return 1
( version_compare '10.0' '-gt' '2.0.0' ); [ "$?" = '0' ] || return 1

# not less/greater-than... but equal
( version_compare '7' '-lt' '7' ); [ "$?" = '1' ] || return 1
( version_compare '7' '-gt' '7' ); [ "$?" = '1' ] || return 1

# String vs. numerical comparison
( version_compare '1.18.1' '-gt' '1.8.1' ); [ "$?" = '0' ] || return 1


# Random tests found on the internet
( version_compare '1' '==' '1' ); [ "$?" = '0' ] || return 1
( version_compare '2.1' '<' '2.2' ); [ "$?" = '0' ] || return 1
( version_compare '3.0.4.10' '>' '3.0.4.2' ); [ "$?" = '0' ] || return 1
( version_compare '4.08' '<' '4.08.01' ); [ "$?" = '0' ] || return 1
( version_compare '3.2.1.9.8144' '>' '3.2' ); [ "$?" = '0' ] || return 1
( version_compare '3.2' '<' '3.2.1.9.8144' ); [ "$?" = '0' ] || return 1
( version_compare '1.2' '<' '2.1' ); [ "$?" = '0' ] || return 1
( version_compare '2.1' '>' '1.2' ); [ "$?" = '0' ] || return 1
( version_compare '5.6.7' '==' '5.6.7' ); [ "$?" = '0' ] || return 1
( version_compare '1.01.1' '==' '1.1.1' ); [ "$?" = '0' ] || return 1
( version_compare '1.1.1' '==' '1.01.1' ); [ "$?" = '0' ] || return 1
( version_compare '1' '!=' '1.0' ); [ "$?" = '0' ] || return 1
( version_compare '1.0.0' '!=' '1.0' ); [ "$?" = '0' ] || return 1

A useful trick here is string indexing.

$ echo "${BASH_VERSION}"
4.4.23(1)-release

$ echo "${BASH_VERSION:0:1}"
4

I use a function that normalizes the numbers and than compare them.

The for loop is necessary to convert octal numbers in version strings to decimal, e.g. 1.08 → 1 8, 1.0030 → 1 30, 2021-02-03 → 2021 2 3...

(Tested with bash 5.0.17

#!/usr/bin/env bash

v() {
  printf "%04d%04d%04d%04d%04d" $(for i in ${1//[^0-9]/ }; do printf "%d " $((10#$i)); done)
}

while read -r test; do
  set -- $test
  printf "$test    "
  eval "if [[ $(v $1) $3 $(v $2) ]] ; then echo true; else echo false; fi"
done << EOF
1              1                   ==
2.1            2.2                  <
3.0.4.10       3.0.4.2              >
4.08           4.08.01              <
3.2.1.9.8144   3.2                  >
3.2            3.2.1.9.8144         <
1.2            2.1                  <
2.1            1.2                  >
5.6.7          5.6.7               ==
1.01.1         1.1.1               ==
1.1.1          1.01.1              ==
1              1.0                 ==
1.0            1                   ==
1.0.2.0        1.0.2               ==
1..0           1.0                 ==
1.0            1..0                ==
1              1                    >
1.2.3~rc2      1.2.3~rc4            >
1.2.3~rc2      1.2.3~rc4           ==
1.2.3~rc2      1.2.3~rc4            <
1.2.3~rc2      1.2.3~rc4           !=
1.2.3~rc2      1.2.3+rc4            <
2021-11-23-rc1 2021-11-23-rc1.1     <
2021-11-23-rc1 2021-11-23-rc1-rf1   <
2021-01-03-rc1 2021-01-04           <
5.0.17(1)-release 5.0.17(2)-release <
EOF

result:

1              1                   ==    true
2.1            2.2                  <    true
3.0.4.10       3.0.4.2              >    true
4.08           4.08.01              <    true
3.2.1.9.8144   3.2                  >    true
3.2            3.2.1.9.8144         <    true
1.2            2.1                  <    true
2.1            1.2                  >    true
5.6.7          5.6.7               ==    true
1.01.1         1.1.1               ==    true
1.1.1          1.01.1              ==    true
1              1.0                 ==    true
1.0            1                   ==    true
1.0.2.0        1.0.2               ==    true
1..0           1.0                 ==    true
1.0            1..0                ==    true
1              1                    >    false
1.2.3~rc2      1.2.3~rc4            >    false
1.2.3~rc2      1.2.3~rc4           ==    false
1.2.3~rc2      1.2.3~rc4            <    true
1.2.3~rc2      1.2.3~rc4           !=    true
1.2.3~rc2      1.2.3+rc4            <    true
2021-11-23-rc1 2021-11-23-rc1.1     <    true
2021-11-23-rc1 2021-11-23-rc1-rf1   <    true
2021-01-03-rc1 2021-01-04           <    true
5.0.17(1)-release 5.0.17(2)-release <    true